Yes, regional stability is one of the many reasons.
Bollocks - regional stability has sweet f-all to do with the EU, despite what the EU administration would like you to think.
The only reason there is peace in Europe is because of NATO - something which pre-dates the EU political concept. Three of the largest contributors to Nato in manpower, money, equipment etc are non-mainland countries: US, UK and Turkey. The only mainland country who takes it seriously are the French.
Oh and the fact the previous uppity German leader was finally removed. Before that the European mainland has had 200+ years of war none of which, funnily enough, were started by the UK but always involved someone from the Mainland who decided their current boundaries weren't adequate.